But you have to cover income taxes and health insurance paid by your company

If so, then Horizon Public Health is the licensing agency.

I would rather hire a lawyer to represent me in court, or a Doctor to assess my health.

This is a safety and health hazard. 

The tenant must produce an ESA letter from a licensed mental health professional or LMHP.

If I was retired and did not have any W-2 or 1099 income I would lean in the other direction as now I have responsibilities like children my partner with the potential of ever-increasing health care costs.

Possibly a little, but to have peace of mind for an elderly relative's health, it's worth it. 

At that point I could do whatever I want without needing to bring in extra income.I know that expenses go up over time, (long term care, health problems, kids' college, etc) but as mortgages in the properties get paid off it frees up a ton of cash flow so my net income goes up as well.For me though, I'll always be working and I hope to never actually retire.

My understanding is that their main concern is that there is no health or safety issues... i.e.

He is 76 yrs old and a smoker otherwise in good health.